<template>
  <div>
    <h1>当前求和为：{{sum}}</h1>
    <!-- v-model.number：将表单收集到的数据强制转换为number类型，然后再赋值。 -->
    <select v-model.number="number">
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script>

    export default {
        name:"Count",
        data() {
            return {
                sum:0,  // 当前的和
                number:1, // 用户选择的数字
            }
        },
        methods:{
            increment(){
                this.sum += this.number;
            },

            decrement(){
                this.sum -= this.number;
            },

            incrementOdd(){
                if(this.sum %2 !==0) this.sum += this.number;
            },

            incrementWait(){
                setTimeout(()=>{
                    this.sum += this.number;
                },500)
            }
        }
    }
</script>

<style>
    button {
        margin-left: 5px;
    }
</style>